1. Field of the Invention
The present invention relates to image processing devices, image processing methods, and image capturing devices that correct aberrations caused by capturing lenses in images captured with the capturing lenses. In particular, the present invention relates to an image processing device, an image processing method, and an image capturing device capable of simultaneously correcting chromatic aberration and distortion aberration caused by a capturing lens.
2. Description Aberration of the Related Art
Video cameras or digital still cameras have been miniaturized rapidly in recent years, and capturing lenses themselves have also been miniaturized. The miniaturization of the capturing lenses increases the aberrations caused by the lenses and therefore quality degradation of captured images is difficult to be suppressed adequately. Specifically, as shown FIG. 6, since each wavelength of red, green, blue components has a different index of refraction when passing through the lenses, a phenomenon occurs in which an image element for the red component is formed outside and an image element for the blue component is formed inside relative to that for the green component. This phenomenon results in color blurring (color shifting) along edges in the image of a subject, even for a black-and-white subject. Japanese Unexamined Patent Application Publication No. 2000-299874 discloses a technique for correcting the aberrations caused by a capturing lens by signal processing.
Moreover, due to distortion aberration, as shown in FIGS. 7A and 7B, straight lines of an image for a linear subject (see FIG. 7A) are disadvantageously curved. The distortion aberration is classified into two types: barrel and pincushion. FIG. 7B illustrates typical barrel distortion.
Conventional electrical correction of the chromatic aberration or distortion aberration mentioned above individually covers only one of them. In order to correct both aberrations, as shown in FIG. 8, these aberrations may be continuously corrected by two correction processes 81 and 82. This correction, however, requires a plurality of reproducing from image memory and recording to the image memory and therefore takes a long time for the whole processing, including the time required for accessing the image memory. As a result, high-speed processing for the correction is difficult to achieve.
In particular, when correction in the horizontal direction and correction in the vertical direction cannot be performed at the same time, the processing time is further increased and thus high-speed processing is more difficult to achieve. This results in decreased product performance, such as a long time between successive image captures in a digital still camera.
Moreover, a long processing time causes an increase in the overall power consumption, including the process for accessing the image memory. This also results in decreased product performance, such as short battery life.